What was the name of the artist that Iris' father used to make £40 million by forging his painting ?

Title: A Monster Calls Author: Patrick Ness Illustrator: Jim Kay Winning Year: 2012
The monster shows up after midnight. It isn't the one Conor has been expecting; the one from his nightmare; the one he has had nearly every night since his mother started her treatment. But this new monster is ancient, and wild, and it wants something ju